Process for preparing methacrylates of fluorinated alcohols

Abstract

The invention relates to a process for preparing methacrylates of fluorinated alcohols, which consists in reacting said alcohols with an excess of methacrylic acid in the presence of phosphoric anhydride, which acts as a catalyst and absorbs the water which has formed. The process is applicable to primary, secondary and tertiary fluorinated alcohols and to alcohols and diols with perfluoroethereal chains.

What is claimed is: 
     
       1. A process for preparing methacrylate of fluorinated alcohols, comprising the fluorinated alcohol is reacted with a methacrylic acid excess in the presence of a phosphoric anhydride excess, at a temperature ranging from 30° to 150° C. 
     
     
       2. The process according to claim 1, wherein the fluorinated alcohol is a primary, secondary or tertiary alcohol of formula: ##STR6## wherein R 1 , R 2  and R 3  same or different, represent a perfluoroalkyl radical, a non-fluorinated aromatic hydrocarbon radical or hydrogen and in which at least one of R 1 , R 2  and R 3  is a perfluoroalkyl radical. 
     
     
       3. The process according to claim 2, wherein R 1 , R 2  and R 3 , same or different, are C 1  -C 4  -perfluoroalkyl or phenyl, tolyl, xylyl radicals. 
     
     
       4. The process according to claim 2, wherein the fluorinated alcohol is trifluoroethanol. 
     
     
       5. The process according to claim 2, wherein the fluorinated alcohol is hexafluoroisopropanol. 
     
     
       6. The process according to claim 2, wherein the fluorinated alcohol is a mixture of alcohols with perfluoropolyethereal chain of formula: ##STR7## in which n and m are integers such that the average molecular weight ranges from 400 to 2,500. 
     
     
       7. The process according to claim 1, wherein the fluorinated alcohol is a diol or a polyol. 
     
     
       8. The process according to claim 6, wherein the fluorinated alcohol is a mixture of diols of formula:   HOCH.sub.2 --CF.sub.2 O(CF.sub.2 --CF.sub.2 O).sub.n (CF.sub.2 O).sub.m --CF.sub.2 --CH.sub.2 OH     in which n and m are integers such that the average molecular weight ranges from 500 to 5,000.   
     
     
       9. The process according to claim 1, wherein the molar ratio between methacrylic acid and OH groups of the alcohol ranges from 1 to 10. 
     
     
       10. The process according to claim 1, wherein the molar ratio between phosphoric anhydride and OH groups of the alcohol ranges from 0.2 to 5. 
     
     
       11. The process according to claim 1, wherein the temperature range is from 80° to 105° C.